At least 30 soldiers serving in Iraq have contracted a skin disease spread by sand flies, prompting a ban on blood donations by all members of the military in Iraq for a year after they return home, health officials said Thursday.

The parasitic disease, leishmaniasis, occurs in two forms. The soldiers have the milder form, which causes skin sores and is curable if promptly treated. The other form of the disease -- believed to account for some reports of Gulf War syndrome after that conflict in 1990-91 -- often causes fever, weight loss and organ damage. It can be fatal.

A few cases have been transmitted through blood transfusions in other countries, but not in the United States. The new policy may divert more than 12,000 blood donors, Pentagon officials said. But some soldiers would have been forbidden from donating anyway because they have been in places where malaria is common.

A similar ban was implemented after the Gulf War, when 32 soldiers got leishmaniasis, including 12 cases of the more serious form of the disease, military officials said.

In a report Thursday by the Centers for Disease Control and Prevention in Atlanta and Walter Reed Army Medical Center in Washington, health officials said the soldiers in the recent outbreak have been treated successfully.

At least 30 soldiers have contracted the skin form of the disease in Iraq this year, plus two apiece in Kuwait and Afghanistan since the beginning of last year, said Dr. Dallas Hack of Walter Reed. They came from the Army, the Air Force and the Marine Corps and included active, reserve and National Guard members.

Most have had a few lesions, often resembling mini-volcanoes, on their arms or legs.

More cases may be forthcoming. The sand fly season runs from May to October, and symptoms often don't appear for a month after infection. "I would expect we would see it for another couple of months," Hack said. "A lot of people are reserves coming back, and they may not see this until they get out of active duty."

Cases of the systemic, more serious, form of the disease also may turn up, said Dr. Kathleen Murray-Leisure, an infectious disease specialist from Pennsylvania who has treated Gulf War veterans.

"What they're seeing so far is the tip of the iceberg," she said. "Whenever you have this many [skin] cases, there are probably [systemic] cases too."

She said systemic leishmaniasis accounts for one-third to one-half of Gulf War syndrome. But Hack said he considers leishmaniasis separate from Gulf War syndrome, a label he reserves for conditions with no specific diagnosis.

Military health officials have instructed soldiers to use insect repellent and insecticide-treated bed nets to protect themselves against parasite-carrying sand flies, Hack said.

Murray-Leisure, who praised those steps, called for one more: clothing that covers the whole body.

"Ideally they would issue scarves to each and every soldier or tell them to wear turbans," she said. "They need to dress like the Arabs."